The present invention is related to a load force bypassing means for a lift truck fork and mast assembly. The bypassing means is disposed between a work engaging fork and carriage assembly having rollers and a generally upright support mast in direct force transmitting relation to effectively isolate the rollers mounting the carriage on the upright support mast from the load forces encountered during normal load crowding operations.
A standard lift truck arrangement has the carriage movably mounted on the upright support mast by sets of carriage rollers which transfer load carried by the forks to the upright support mast. Normal crowding or forcible engagement of the forks with the load produces particularly high forces which are normally transmitted by the rollers to the upright support mast causing damage and early failure of these components.
Load crowding is the act of loading the lift forks by forcibly engaging the forks with the load while using the lift truck to push the forks under the load. It is normally performed with the carriage and forks raised slightly a few inches to prevent the forks from dragging on debris or the earth. Dragging forks impede the motion of the lift truck. It is normal practice in logging applications to use full tractive effort to crowd the load against the forks while tilting the fork and mast assembly backwards to lift the load. This subjects the carriage rollers to impact loading due to the tractive effort of the lift truck. Standard lift truck arrangements are plagued by damage to the rollers and upright support mast in this type of operation.
Uneven loading of the forks in logging applications is also a problem with standard lift trucks. Uneven loading occurs because of uneven fork contact with irregularly shaped logs. This causes misalignment of the sets of carriage rollers with respect to the upright support mast which accelerates wear.
The present invention improves upon the general features of the lift truck mast by isolating the carriage rollers from the load forces encountered during normal load crowding operations.